In this thesis, we successfully fabricated GOLD ( gate-overlapped LDD ) polycrystalline silicon thin-film transistors ( poly-Si TFTs ) with selectively deposited W spacers. Under appropriate deposition conditions, tungsten ( W ) films can be selectively deposited on poly-Si gate electrodes to form spacers without any additional etching process. Compared with the conventional poly-TFTs without LDD structures, our devices effectively lower the leakage current and sustain a comparable on current. The transconductance of our devices is compatible to that of conventional devices, because W-spacer acts as a part of gate electrode to induce channel when the device is operated under ON state.
To further study the characteristics of W-spacer TFTs, devices with different channel thickness, spacer thickness and LDD dopant density are fabricated. It is found that thinner channel, thicker spacer and lightly doped LDD implant can effectively suppress the floating body effect and also the kink effect. By comparing device performances after plasma passivation, it is also found that small-dimensional devices have better passivation effect.
Finally, the hot-carrier reliability of W-spacer TFTs is also studied. Due to the reduced electric filed on the drain side, W-spacer TFTs have better reliability than the conventional counterparts.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0730102-171841 |
| Date | 30 July 2002 |
| Creators | Kang, Chih-Kai |
| Contributors | Chao-Hsih Chien, Ting-Chang Chang, Chin-fu Liu, Po-Tsun Liu, Dong-Po Wang |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0730102-171841 |
| Rights | unrestricted, Copyright information available at source archive |
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